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STM Bluetooth LE chip accelerates smart connections

Steve Rogerson
July 6, 2017

A Bluetooth Low Energy system-on-chip from Swiss semiconductor company ST Microelectronics aims to accelerate the spread of connected smart objects throughout homes, shopping areas, industry, toys, gaming, personal healthcare and infrastructure.
Built into all new mobile phones, tablets and computers, Bluetooth LE wireless technology lets consumers interact with any BLE-enabled object from their own devices. Similarly, service providers can connect assets to the cloud for service delivery and data collection.
STM sees important opportunities for BLE-connected applications that are simple, functionally focused and can operate on a button cell for months or years. The BlueNRG-2 chip is said to meet these needs with its power-efficient programmable processor and low-power features including a frugal standby mode.
The high RF signal strength saves system power by ensuring wireless communications, and on-chip memory for BLE software and application code simplifies system design by saving external memory components.
The device is Bluetooth 5.0-certified, which ensures interoperability with the latest generation of smartphones, and supports features such as security, privacy and extended packet length for faster data transfer.
“The BlueNRG-2 ushers in an era of connected smart things all around us, enabling secure, reliable and energy-efficient interaction with any object, like a toothbrush or lighting switch, from our mobile devices,” said Benedetto Vigna, executive vice president at ST Microelectronics. “Moreover, the objects can benefit from simple construction, fully sealed if necessary, and yet fully interoperable through natural voice control or the feature-rich and stylish user interface of an Android or iOS smart application.”
A software development kit is available, featuring the BlueNRG Navigator graphical user interface, which makes it easier for designers and innovators to create the next generation of connected devices with the chip.
The device is available now in a 32-pin QFN. Further options will be introduced later in the year, offering more GPIO in a 48-pin QFN and a small 2.6 by 2.7mm WLCSP chip-scale package.
It uses an ARM Cortex-M0 core to provide 32bit processing performance. Other integrated features include cryptographic processing, power management, clock management and up to 256kbyte of flash memory giving flexibility to handle code and data storage. Multiple power-saving modes, including standby mode drawing just 0.5µA, help meet functional requirements with a low power budget.
The integrated BLE radio with +8dBm RF output power increases communications range and saves overall energy consumption by avoiding data errors and retries. The device is specified for operation up to +105°C, allowing use in a wide range of scenarios including automotive environments.
Developers using the device can take advantage of seamless interconnection with the STM MEMS sensor portfolio, which includes accelerometers, gyroscopes, magnetometers, inertial measurement units, pressure sensors and other environmental sensors. An integrated two-channel, 10bit analogue-to-digital converter provides a convenient interface for analogue front-end transducers, and a pulse digital modulation interface simplifies connecting a digital MEMS microphone for natural-speech voice-controlled applications.
The increased memory size and the efficient core architecture allows running STM Open MEMS libraries with low impact on the overall power consumption. The sensors and libraries together enable developers to implement capabilities such as gesture recognition and activity tracking.
STM has also developed a dedicated miniature balun for the devices. Integrating a matching network and harmonics filter, the balun simplifies RF complexity and provides optimised link budget in a less than 1.2mm² footprint. Designed on non-conductive glass substrate, it offers low dispersion over temperature.
The BlueNRG Navigator GUI simplifies and streamlines device configuration, setup and testing, and enables makers or developers to get started and implement new ideas for smart devices without requiring any specific RF or BLE skills. The intuitive graphical interface is said to let users become productive in just a few hours.
Application examples, code snippets and tool support allow coding to begin quickly using the BlueNRG-2 evaluation kit. The kit contains MEMS sensors, LEDs, push-buttons and programming interfacing to run the provided demonstration software out of the box. An Arduino-compatible connector is also on board, which allows development of more complex applications by adding extra expansion boards.
STM and Security Platform, a South Korea-based technology innovator, are working together to bring robust, efficient and easy-to-use security to IoT devices.